Tuesday, October 09, 2007

Tamino has an interesting post on Arctic and Antarctic ice extent. Now if you stare at the stuff long enough you realize that the maximum is pretty much always the same

but after a bit of thought, you realize that the Arctic is a closed ocean and it pretty much freezes completely over each year (PS the above only goes to 2000 and does not show the 2000 - 2007 decline. Tamino has the more recent information). Still, this is not completely the case, and analysis shows that even in the winter the ice area is declining.we can learn even more by looking at maps of the maximum ice concentration from the National Sea Ice Data Center. The map on the left is from Feb 1979 and the one on the right from Feb 2007.

The major differences are in the areas north of the Norway/Russian border. But when we look at the minimum extent from 2007 we see that it is the area between Alaska and Siberia that is relatively clear of ice.

So, we still need to decide whether our bet with Belette is in carrots or in pounds. Hmm, maybe we are looking at the wrong thing. During the autumn and winter the Arctic freezes over, but HOW THICK IS THE ICE. The thicker the ice, the more heat needed to melt the stuff in the summer. The thinner the less.

There are not very many measurements of ice thickness trends for obvious reasons. The best come from Rothrock at the University of Washington who analyzed data from nuclear submarine cruises (Al Gore played a key role in getting these released). Here is what he came up with.

What is a bunny to do? Well we will chew a few carrots and keep a close watch on how rapid the freeze is and try and figure out how deep.

31 comments:

Steve Bloom
said...

The last sentence in Rothrock et al (1999) is, IIRC, a reference to the Navy's refusal to cough up everything they have. Of course the Navy's own sea ice modeler (Maslowski) has that data, and he's the one who's made the most extreme projections of ice loss (although sans publication). Peter Wadhams has more recent information from Royal Navy sub cruises, but he hasn't published anything lately. Also, I'm not sure how terribly relevant Rothrock et al is to the present trend since it predates the inflection point that happened around 2000. Finally, since there is very little multi-year ice remaining, is the thickness data still especially important?

Looking around a bit, it appears that Rothrock's home page has much more current and complete stuff (still missing the secret data, though).

It'd be cute to see CA go up against the Russian, Royal and US Navy secrecy rules.

The "Gore Box" declassified maybe a third of the Arctic Ocean and all that was released thanks to then VP Gore's pressure for opening up the data.

CA should go after the Russians for their data, none of it has been released.

There's a lot of work at the Navy Postgrad School in Monterey and on their website. We can hope the anonymite from CA is correct that many papers are indeed being written (their thesis papers are mostly online) even if the underlying ice depth measurements are still classified secret.

For this, our climate data collection instrument is the nuclear attack or defense submarine fleet loaded with Trident MIRVs and the Russian equivalent, all hiding under the diminishing ice, kept hidden under the ice to be able to make the planet-killer third wave nuclear war move -- the "greater madman" mutually assured destruction retaliatory strike back meant to deter a first strike by anyone.

I'm sure CA can get the data by asking nicely.

Nitwits.

Say, does the killfile work on IP numbers? I don't want to ignore any anonymouse with a brain.

The thickness data is important, because the thickness of the new ice predicts the next year's melt.'

Understood, but from the standpoint of assessing the impact of climate change, the percent ice mass loss over the past 40 years is even more significant than percent extent decrease or percent thickness decrease alone.

"submarine fleet loaded with Trident MIRVs and the Russian equivalent, all hiding under the diminishing ice, kept hidden under the ice"

That would make a funny cartoon.

Flash forward 20 years when a couple hundred US and Russian submarines are all trying to hide under the one remaining piece of arctic ice the size of a football field -- with all the remaining polar bears crowded on top, of course.

Hey, that gives me an idea. maybe we can paint all the submarines white on top and keep them cruising around on the surface. that way the polar bears can use them as hunting platforms. The submarines would certainly be more useful in the latter capacity than they are now.

Hank, there's a possibility here of serious jail time for some of the auditors if they're persistent enough about that data, so let's not be too discouraging. Seriously, since the data they're not releasing is for the 200-mile economic zones, I have a feeling that military secrecy is just an excuse. I suspect certain privileged parties may have access.

Eli, I didn't have a chance to look at the other Rothrock papers yet, but the 1999 paper is for summer thickness. IOW, is there any useful information about the thickness of the recovered ice?

The earlier mentioned seaice.dk has great charts about this. You can go to september and apply date and then change the year and apply date again to check it. Years vary a lot, sometimes the northeast passage has lots of ice and sometimes a lot less. I think it was completely clear in 2005 for example, there was less ice than in 2007. But then there was ice elsewhere.

http://www.seaice.dk/test.N/use the quickscat data from the top menu..

This doesn't of course mean that there are no trends in the area, just that the other signals change a lot more and lot more clearly, and we have to make sure that the area isn't a side effect of these other signals like the different location of the ice in different years.But look at the data yourself. You find the years are quite different.

Sorry to interupt the thread, but it looks like McIntyre is moving on to push some other bean -- again, (because the "Hansen bean" has yielded a sprout rather than a giant bean stalk up to the sky like he thought it would):

"John V has posted some graphics recently arguing that CRN1-2 yielded pretty much the same results as major temperature indices and, in some sense, vindicated these results. As Gavin Schmidt has pointed out, the U.S. is only 2% of the world’s surface; and as I’ve observed on many occasions, the statistical methodologies and data quality in the U.S. are different from the ROW, as is the history.

I’ve been focussing more on ROW issues recently rather than U.S. issues..."

and found that "The Navy's Arctic Submarine Laboratory (ASL) had the foresight to save all ice draft data starting with the first cruise in 1958 and continuing until the present.

There have been over 70 cruises, roughly one per year, each lasting some 20 to 40 days and transiting much of the Arctic Ocean, sometimes once, sometimes twice. Many of these draft data have been released for a region covering about half of the Arctic Ocean and are archived for public use at the National Snow and Ice Data Center (NSIDC)."

Abstract: In this project, we have shown that methane a "greenhouse gas" is present throughout the arctic ocean. In surveys conducted mainly between 120 and 230 degrees longitude using the U.S. Navy nuclear submarine Pargo (1993) and the Canadian ice breaker Louis S. St. Laurent (1994), we showed that methane is present in water beneath the permanent ice at variable concentrations near the surface that usually exceed the atmospheric equilibrium concentrations of about 4 nanomolar by factors of about 1.3 to 4. Methane concentrations decrease with depth.

sorry that I can't find it, but a report out of Norway last month featured in an article, which said that the sea ice this year around the Kara/Laptev seas was about a metre think. In previous year it has been around two metres think at the comparable time of year. This is the only material I have found on the subject since Rothrock (there's a discussion of how valid the R. data is in ACIA or ICARP). There was no formal finding, but the implication is that the Summer single year ice may be only half as think as previously, across large areas of the Arctic.

Revision; that was Schauer at the AWI (Germany, not Norway): http://news.mongabay.com/2007/0914-sea_ice.html

There was a paper on '05 by a team from Southampton which used data from HMS Tireless, and stuff from Haas, Zhang, and assorted others; much of it is about estimating thickness from assorted satellite data; only two base their findings on direct measurement.

To 2006, average thickness probably declined by about 43%. This comes from a comparable decline in multi season ice. There's nothing much on how thick the single year ice 'should' be, but ~1m seems a reasonable average.

I recently gave a presentation to a friend's Audubon group titled "The Global Warming Debate." I've added a narration and converted it to a video. My goal was to create something that is both easy to understand and covers the topics that people might hear on TV , on the Internet, or in skeptical books. It should be a good companion to any (good) documentary on Global Warming. The popular press and blogosphere obsesses over these details, so it's important for the average person to be aware of the actual facts and evidence.

I'm hoping to get feedback so that I can correct any significant problems or inaccuracies. I don't want to be accused of spreading misinformation.

It is broken into 5 parts, but if you watch it from start to finish it is about 3 and 1/2 hours. So, it is not insignificant in content. While recording the narration, I went from not sick to sick to not sick so my voice can be pretty hoarse in some places. I also make no claims to my skill as a narrator.

I spent some time at the library and purchased a number of "historical" books. For example, I spent a lot of time documenting the "Volcanoes cause more ____ than all of mankind" skeptical claim, which many might find amusing. I retrieved some additional "global cooling" articles from the '70s. I have Hansen's entire 1987 Senate testimony (his '88 testimony was, sadly, missing). I have the original graph from Lamb first published in 1965 and covering the temperature of Central England. This eventually became the "global temperature of the last 1000 years" chart from the first IPCC report. I have a lot of other graphics and charts taken from journal articles, and swiped from the internet. Some should be familiar, and I hope that no one minds that I used them (I cited the sources). I have more than what is in the presentation, and can provide these documents to those who request them. However, my first emphasis is on creating a reasonably final version of this presentation.

I've uploaded the parts to one of those free web hosting sites. It is here:cce.000webhost.org

This site may not be adequate, but for now it will have to do. I picked it mainly for its high monthly bandwidth limits, but it seems pretty sluggish sometimes.(I looked at Google video but the videos are too small to provide the text based detail necessary.)

The video uses the H.264 MPEG4 codec and requires a recent version of Quicktime. It is 640X480 which is large enough for the detail I needed. I went to great lengths to make sure it will play in real time over a dialup modem. I might make a “broadband” version that will be 800X600.

Because it is still a draft, I ask everyone not to publicize or distribute it, beyond the blog sites that I am posting this to.

Please send me any feedback that you wish (email address on site). I have worked on this for 5 months, so I am not eager to turn it inside out. I am more interested in correcting significant errors.

Excellent article, it will be interesting to see, if the winter trajectory will mimic the Summer again, or buck it, like it did between 1998- 2004. If not we could see a highly accelerated decline for the next few years.Grave maintenance and Care - Ireland!

Rabett Run

Subscribe Rabett Run

The Bunny Trail By Email

Contributors

Eli Rabett

Eli Rabett, a not quite failed professorial techno-bunny who finally handed in the keys and retired from his wanna be research university. The students continue to be naive but great people and the administrators continue to vary day-to-day between homicidal and delusional without Eli's help. Eli notices from recent political developments that this behavior is not limited to administrators. His colleagues retain their curious inability to see the holes that they dig for themselves. Prof. Rabett is thankful that they, or at least some of them occasionally heeded his pointing out the implications of the various enthusiasms that rattle around the department and school. Ms. Rabett is thankful that Prof. Rabett occasionally heeds her pointing out that he is nuts.